[ViewVC] Diff of: cvs/libev/ev.3

Comparing libev/ev.3 (file contents):
Revision 1.7 by root, Fri Nov 23 08:36:35 2007 UTC vs.
Revision 1.11 by root, Sat Nov 24 07:14:26 2007 UTC

…		…
127	.\}	127	.\}
128	.rm #[ #] #H #V #F C	128	.rm #[ #] #H #V #F C
129	.\" ========================================================================	129	.\" ========================================================================
130	.\"	130	.\"
131	.IX Title ""<STANDARD INPUT>" 1"	131	.IX Title ""<STANDARD INPUT>" 1"
132	.TH "<STANDARD INPUT>" 1 "2007-11-23" "perl v5.8.8" "User Contributed Perl Documentation"	132	.TH "<STANDARD INPUT>" 1 "2007-11-24" "perl v5.8.8" "User Contributed Perl Documentation"
133	.SH "NAME"	133	.SH "NAME"
134	libev \- a high performance full\-featured event loop written in C	134	libev \- a high performance full\-featured event loop written in C
135	.SH "SYNOPSIS"	135	.SH "SYNOPSIS"
136	.IX Header "SYNOPSIS"	136	.IX Header "SYNOPSIS"
137	.Vb 1	137	.Vb 1
…		…
173	.IX Header "TIME REPRESENTATION"	173	.IX Header "TIME REPRESENTATION"
174	Libev represents time as a single floating point number, representing the	174	Libev represents time as a single floating point number, representing the
175	(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near	175	(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
176	the beginning of 1970, details are complicated, don't ask). This type is	176	the beginning of 1970, details are complicated, don't ask). This type is
177	called \f(CW\(C`ev_tstamp\(C'\fR, which is what you should use too. It usually aliases	177	called \f(CW\(C`ev_tstamp\(C'\fR, which is what you should use too. It usually aliases
178	to the double type in C.	178	to the \f(CW\(C`double\(C'\fR type in C, and when you need to do any calculations on
		179	it, you should treat it as such.
179	.SH "GLOBAL FUNCTIONS"	180	.SH "GLOBAL FUNCTIONS"
180	.IX Header "GLOBAL FUNCTIONS"	181	.IX Header "GLOBAL FUNCTIONS"
181	These functions can be called anytime, even before initialising the	182	These functions can be called anytime, even before initialising the
182	library in any way.	183	library in any way.
183	.IP "ev_tstamp ev_time ()" 4	184	.IP "ev_tstamp ev_time ()" 4
…		…
199	.Sp	200	.Sp
200	Usually, it's a good idea to terminate if the major versions mismatch,	201	Usually, it's a good idea to terminate if the major versions mismatch,
201	as this indicates an incompatible change. Minor versions are usually	202	as this indicates an incompatible change. Minor versions are usually
202	compatible to older versions, so a larger minor version alone is usually	203	compatible to older versions, so a larger minor version alone is usually
203	not a problem.	204	not a problem.
		205	.Sp
		206	Example: make sure we haven't accidentally been linked against the wrong
		207	version:
		208	.Sp
		209	.Vb 3
		210	\& assert (("libev version mismatch",
		211	\& ev_version_major () == EV_VERSION_MAJOR
		212	\& && ev_version_minor () >= EV_VERSION_MINOR));
		213	.Ve
204	.IP "unsigned int ev_supported_backends ()" 4	214	.IP "unsigned int ev_supported_backends ()" 4
205	.IX Item "unsigned int ev_supported_backends ()"	215	.IX Item "unsigned int ev_supported_backends ()"
206	Return the set of all backends (i.e. their corresponding \f(CW\(C`EV_BACKEND_\*(C'\fR	216	Return the set of all backends (i.e. their corresponding \f(CW\(C`EV_BACKEND_\*(C'\fR
207	value) compiled into this binary of libev (independent of their	217	value) compiled into this binary of libev (independent of their
208	availability on the system you are running on). See \f(CW\(C`ev_default_loop\(C'\fR for	218	availability on the system you are running on). See \f(CW\(C`ev_default_loop\(C'\fR for
209	a description of the set values.	219	a description of the set values.
		220	.Sp
		221	Example: make sure we have the epoll method, because yeah this is cool and
		222	a must have and can we have a torrent of it please!!!11
		223	.Sp
		224	.Vb 2
		225	\& assert (("sorry, no epoll, no sex",
		226	\& ev_supported_backends () & EVBACKEND_EPOLL));
		227	.Ve
210	.IP "unsigned int ev_recommended_backends ()" 4	228	.IP "unsigned int ev_recommended_backends ()" 4
211	.IX Item "unsigned int ev_recommended_backends ()"	229	.IX Item "unsigned int ev_recommended_backends ()"
212	Return the set of all backends compiled into this binary of libev and also	230	Return the set of all backends compiled into this binary of libev and also
213	recommended for this platform. This set is often smaller than the one	231	recommended for this platform. This set is often smaller than the one
214	returned by \f(CW\(C`ev_supported_backends\(C'\fR, as for example kqueue is broken on	232	returned by \f(CW\(C`ev_supported_backends\(C'\fR, as for example kqueue is broken on
215	most BSDs and will not be autodetected unless you explicitly request it	233	most BSDs and will not be autodetected unless you explicitly request it
216	(assuming you know what you are doing). This is the set of backends that	234	(assuming you know what you are doing). This is the set of backends that
217	\&\f(CW\(C`EVFLAG_AUTO\(C'\fR will probe for.	235	libev will probe for if you specify no backends explicitly.
		236	.IP "unsigned int ev_embeddable_backends ()" 4
		237	.IX Item "unsigned int ev_embeddable_backends ()"
		238	Returns the set of backends that are embeddable in other event loops. This
		239	is the theoretical, all\-platform, value. To find which backends
		240	might be supported on the current system, you would need to look at
		241	\&\f(CW\(C`ev_embeddable_backends () & ev_supported_backends ()\(C'\fR, likewise for
		242	recommended ones.
		243	.Sp
		244	See the description of \f(CW\(C`ev_embed\(C'\fR watchers for more info.
218	.IP "ev_set_allocator (void (cb)(void *ptr, long size))" 4	245	.IP "ev_set_allocator (void (cb)(void *ptr, long size))" 4
219	.IX Item "ev_set_allocator (void (cb)(void *ptr, long size))"	246	.IX Item "ev_set_allocator (void (cb)(void *ptr, long size))"
220	Sets the allocation function to use (the prototype is similar to the	247	Sets the allocation function to use (the prototype is similar to the
221	realloc C function, the semantics are identical). It is used to allocate	248	realloc C function, the semantics are identical). It is used to allocate
222	and free memory (no surprises here). If it returns zero when memory	249	and free memory (no surprises here). If it returns zero when memory
…		…
224	destructive action. The default is your system realloc function.	251	destructive action. The default is your system realloc function.
225	.Sp	252	.Sp
226	You could override this function in high-availability programs to, say,	253	You could override this function in high-availability programs to, say,
227	free some memory if it cannot allocate memory, to use a special allocator,	254	free some memory if it cannot allocate memory, to use a special allocator,
228	or even to sleep a while and retry until some memory is available.	255	or even to sleep a while and retry until some memory is available.
		256	.Sp
		257	Example: replace the libev allocator with one that waits a bit and then
		258	retries: better than mine).
		259	.Sp
		260	.Vb 6
		261	\& static void *
		262	\& persistent_realloc (void *ptr, long size)
		263	\& {
		264	\& for (;;)
		265	\& {
		266	\& void *newptr = realloc (ptr, size);
		267	.Ve
		268	.Sp
		269	.Vb 2
		270	\& if (newptr)
		271	\& return newptr;
		272	.Ve
		273	.Sp
		274	.Vb 3
		275	\& sleep (60);
		276	\& }
		277	\& }
		278	.Ve
		279	.Sp
		280	.Vb 2
		281	\& ...
		282	\& ev_set_allocator (persistent_realloc);
		283	.Ve
229	.IP "ev_set_syserr_cb (void (cb)(const char msg));" 4	284	.IP "ev_set_syserr_cb (void (cb)(const char msg));" 4
230	.IX Item "ev_set_syserr_cb (void (cb)(const char msg));"	285	.IX Item "ev_set_syserr_cb (void (cb)(const char msg));"
231	Set the callback function to call on a retryable syscall error (such	286	Set the callback function to call on a retryable syscall error (such
232	as failed select, poll, epoll_wait). The message is a printable string	287	as failed select, poll, epoll_wait). The message is a printable string
233	indicating the system call or subsystem causing the problem. If this	288	indicating the system call or subsystem causing the problem. If this
234	callback is set, then libev will expect it to remedy the sitution, no	289	callback is set, then libev will expect it to remedy the sitution, no
235	matter what, when it returns. That is, libev will generally retry the	290	matter what, when it returns. That is, libev will generally retry the
236	requested operation, or, if the condition doesn't go away, do bad stuff	291	requested operation, or, if the condition doesn't go away, do bad stuff
237	(such as abort).	292	(such as abort).
		293	.Sp
		294	Example: do the same thing as libev does internally:
		295	.Sp
		296	.Vb 6
		297	\& static void
		298	\& fatal_error (const char *msg)
		299	\& {
		300	\& perror (msg);
		301	\& abort ();
		302	\& }
		303	.Ve
		304	.Sp
		305	.Vb 2
		306	\& ...
		307	\& ev_set_syserr_cb (fatal_error);
		308	.Ve
238	.SH "FUNCTIONS CONTROLLING THE EVENT LOOP"	309	.SH "FUNCTIONS CONTROLLING THE EVENT LOOP"
239	.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP"	310	.IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP"
240	An event loop is described by a \f(CW\(C`struct ev_loop \*(C'\fR. The library knows two	311	An event loop is described by a \f(CW\(C`struct ev_loop \*(C'\fR. The library knows two
241	types of such loops, the \fIdefault\fR loop, which supports signals and child	312	types of such loops, the \fIdefault\fR loop, which supports signals and child
242	events, and dynamically created loops which do not.	313	events, and dynamically created loops which do not.
…		…
256	.Sp	327	.Sp
257	If you don't know what event loop to use, use the one returned from this	328	If you don't know what event loop to use, use the one returned from this
258	function.	329	function.
259	.Sp	330	.Sp
260	The flags argument can be used to specify special behaviour or specific	331	The flags argument can be used to specify special behaviour or specific
261	backends to use, and is usually specified as \f(CW0\fR (or \s-1EVFLAG_AUTO\s0).	332	backends to use, and is usually specified as \f(CW0\fR (or \f(CW\(C`EVFLAG_AUTO\(C'\fR).
262	.Sp	333	.Sp
263	It supports the following flags:	334	The following flags are supported:
264	.RS 4	335	.RS 4
265	.ie n .IP """EVFLAG_AUTO""" 4	336	.ie n .IP """EVFLAG_AUTO""" 4
266	.el .IP "\f(CWEVFLAG_AUTO\fR" 4	337	.el .IP "\f(CWEVFLAG_AUTO\fR" 4
267	.IX Item "EVFLAG_AUTO"	338	.IX Item "EVFLAG_AUTO"
268	The default flags value. Use this if you have no clue (it's the right	339	The default flags value. Use this if you have no clue (it's the right
…		…
312	.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4	383	.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
313	.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"	384	.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
314	Kqueue deserves special mention, as at the time of this writing, it	385	Kqueue deserves special mention, as at the time of this writing, it
315	was broken on all BSDs except NetBSD (usually it doesn't work with	386	was broken on all BSDs except NetBSD (usually it doesn't work with
316	anything but sockets and pipes, except on Darwin, where of course its	387	anything but sockets and pipes, except on Darwin, where of course its
317	completely useless). For this reason its not being \(L"autodetected\(R" unless	388	completely useless). For this reason its not being \(L"autodetected\(R"
318	you explicitly specify the flags (i.e. you don't use \s-1EVFLAG_AUTO\s0).	389	unless you explicitly specify it explicitly in the flags (i.e. using
		390	\&\f(CW\(C`EVBACKEND_KQUEUE\(C'\fR).
319	.Sp	391	.Sp
320	It scales in the same way as the epoll backend, but the interface to the	392	It scales in the same way as the epoll backend, but the interface to the
321	kernel is more efficient (which says nothing about its actual speed, of	393	kernel is more efficient (which says nothing about its actual speed, of
322	course). While starting and stopping an I/O watcher does not cause an	394	course). While starting and stopping an I/O watcher does not cause an
323	extra syscall as with epoll, it still adds up to four event changes per	395	extra syscall as with epoll, it still adds up to four event changes per
…		…
346	.Sp	418	.Sp
347	If one or more of these are ored into the flags value, then only these	419	If one or more of these are ored into the flags value, then only these
348	backends will be tried (in the reverse order as given here). If none are	420	backends will be tried (in the reverse order as given here). If none are
349	specified, most compiled-in backend will be tried, usually in reverse	421	specified, most compiled-in backend will be tried, usually in reverse
350	order of their flag values :)	422	order of their flag values :)
		423	.Sp
		424	The most typical usage is like this:
		425	.Sp
		426	.Vb 2
		427	\& if (!ev_default_loop (0))
		428	\& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		429	.Ve
		430	.Sp
		431	Restrict libev to the select and poll backends, and do not allow
		432	environment settings to be taken into account:
		433	.Sp
		434	.Vb 1
		435	\& ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
		436	.Ve
		437	.Sp
		438	Use whatever libev has to offer, but make sure that kqueue is used if
		439	available (warning, breaks stuff, best use only with your own private
		440	event loop and only if you know the \s-1OS\s0 supports your types of fds):
		441	.Sp
		442	.Vb 1
		443	\& ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
		444	.Ve
351	.RE	445	.RE
352	.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4	446	.IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4
353	.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"	447	.IX Item "struct ev_loop *ev_loop_new (unsigned int flags)"
354	Similar to \f(CW\(C`ev_default_loop\(C'\fR, but always creates a new event loop that is	448	Similar to \f(CW\(C`ev_default_loop\(C'\fR, but always creates a new event loop that is
355	always distinct from the default loop. Unlike the default loop, it cannot	449	always distinct from the default loop. Unlike the default loop, it cannot
356	handle signal and child watchers, and attempts to do so will be greeted by	450	handle signal and child watchers, and attempts to do so will be greeted by
357	undefined behaviour (or a failed assertion if assertions are enabled).	451	undefined behaviour (or a failed assertion if assertions are enabled).
		452	.Sp
		453	Example: try to create a event loop that uses epoll and nothing else.
		454	.Sp
		455	.Vb 3
		456	\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
		457	\& if (!epoller)
		458	\& fatal ("no epoll found here, maybe it hides under your chair");
		459	.Ve
358	.IP "ev_default_destroy ()" 4	460	.IP "ev_default_destroy ()" 4
359	.IX Item "ev_default_destroy ()"	461	.IX Item "ev_default_destroy ()"
360	Destroys the default loop again (frees all memory and kernel state	462	Destroys the default loop again (frees all memory and kernel state
361	etc.). This stops all registered event watchers (by not touching them in	463	etc.). This stops all registered event watchers (by not touching them in
362	any way whatsoever, although you cannot rely on this :).	464	any way whatsoever, although you cannot rely on this :).
…		…
396	Returns one of the \f(CW\(C`EVBACKEND_\*(C'\fR flags indicating the event backend in	498	Returns one of the \f(CW\(C`EVBACKEND_\*(C'\fR flags indicating the event backend in
397	use.	499	use.
398	.IP "ev_tstamp ev_now (loop)" 4	500	.IP "ev_tstamp ev_now (loop)" 4
399	.IX Item "ev_tstamp ev_now (loop)"	501	.IX Item "ev_tstamp ev_now (loop)"
400	Returns the current \(L"event loop time\(R", which is the time the event loop	502	Returns the current \(L"event loop time\(R", which is the time the event loop
401	got events and started processing them. This timestamp does not change	503	received events and started processing them. This timestamp does not
402	as long as callbacks are being processed, and this is also the base time	504	change as long as callbacks are being processed, and this is also the base
403	used for relative timers. You can treat it as the timestamp of the event	505	time used for relative timers. You can treat it as the timestamp of the
404	occuring (or more correctly, the mainloop finding out about it).	506	event occuring (or more correctly, libev finding out about it).
405	.IP "ev_loop (loop, int flags)" 4	507	.IP "ev_loop (loop, int flags)" 4
406	.IX Item "ev_loop (loop, int flags)"	508	.IX Item "ev_loop (loop, int flags)"
407	Finally, this is it, the event handler. This function usually is called	509	Finally, this is it, the event handler. This function usually is called
408	after you initialised all your watchers and you want to start handling	510	after you initialised all your watchers and you want to start handling
409	events.	511	events.
410	.Sp	512	.Sp
411	If the flags argument is specified as 0, it will not return until either	513	If the flags argument is specified as \f(CW0\fR, it will not return until
412	no event watchers are active anymore or \f(CW\(C`ev_unloop\(C'\fR was called.	514	either no event watchers are active anymore or \f(CW\(C`ev_unloop\(C'\fR was called.
		515	.Sp
		516	Please note that an explicit \f(CW\(C`ev_unloop\(C'\fR is usually better than
		517	relying on all watchers to be stopped when deciding when a program has
		518	finished (especially in interactive programs), but having a program that
		519	automatically loops as long as it has to and no longer by virtue of
		520	relying on its watchers stopping correctly is a thing of beauty.
413	.Sp	521	.Sp
414	A flags value of \f(CW\(C`EVLOOP_NONBLOCK\(C'\fR will look for new events, will handle	522	A flags value of \f(CW\(C`EVLOOP_NONBLOCK\(C'\fR will look for new events, will handle
415	those events and any outstanding ones, but will not block your process in	523	those events and any outstanding ones, but will not block your process in
416	case there are no events and will return after one iteration of the loop.	524	case there are no events and will return after one iteration of the loop.
417	.Sp	525	.Sp
418	A flags value of \f(CW\(C`EVLOOP_ONESHOT\(C'\fR will look for new events (waiting if	526	A flags value of \f(CW\(C`EVLOOP_ONESHOT\(C'\fR will look for new events (waiting if
419	neccessary) and will handle those and any outstanding ones. It will block	527	neccessary) and will handle those and any outstanding ones. It will block
420	your process until at least one new event arrives, and will return after	528	your process until at least one new event arrives, and will return after
421	one iteration of the loop.	529	one iteration of the loop. This is useful if you are waiting for some
		530	external event in conjunction with something not expressible using other
		531	libev watchers. However, a pair of \f(CW\(C`ev_prepare\(C'\fR/\f(CW\(C`ev_check\(C'\fR watchers is
		532	usually a better approach for this kind of thing.
422	.Sp	533	.Sp
423	This flags value could be used to implement alternative looping
424	constructs, but the \f(CW\(C`prepare\(C'\fR and \f(CW\(C`check\(C'\fR watchers provide a better and
425	more generic mechanism.
426	.Sp
427	Here are the gory details of what ev_loop does:	534	Here are the gory details of what \f(CW\(C`ev_loop\(C'\fR does:
428	.Sp	535	.Sp
429	.Vb 15	536	.Vb 18
430	\& 1. If there are no active watchers (reference count is zero), return.	537	\& * If there are no active watchers (reference count is zero), return.
431	\& 2. Queue and immediately call all prepare watchers.	538	\& - Queue prepare watchers and then call all outstanding watchers.
432	\& 3. If we have been forked, recreate the kernel state.	539	\& - If we have been forked, recreate the kernel state.
433	\& 4. Update the kernel state with all outstanding changes.	540	\& - Update the kernel state with all outstanding changes.
434	\& 5. Update the "event loop time".	541	\& - Update the "event loop time".
435	\& 6. Calculate for how long to block.	542	\& - Calculate for how long to block.
436	\& 7. Block the process, waiting for events.	543	\& - Block the process, waiting for any events.
		544	\& - Queue all outstanding I/O (fd) events.
437	\& 8. Update the "event loop time" and do time jump handling.	545	\& - Update the "event loop time" and do time jump handling.
438	\& 9. Queue all outstanding timers.	546	\& - Queue all outstanding timers.
439	\& 10. Queue all outstanding periodics.	547	\& - Queue all outstanding periodics.
440	\& 11. If no events are pending now, queue all idle watchers.	548	\& - If no events are pending now, queue all idle watchers.
441	\& 12. Queue all check watchers.	549	\& - Queue all check watchers.
442	\& 13. Call all queued watchers in reverse order (i.e. check watchers first).	550	\& - Call all queued watchers in reverse order (i.e. check watchers first).
		551	\& Signals and child watchers are implemented as I/O watchers, and will
		552	\& be handled here by queueing them when their watcher gets executed.
443	\& 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	553	\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
444	\& was used, return, otherwise continue with step #1.	554	\& were used, return, otherwise continue with step *.
		555	.Ve
		556	.Sp
		557	Example: queue some jobs and then loop until no events are outsanding
		558	anymore.
		559	.Sp
		560	.Vb 4
		561	\& ... queue jobs here, make sure they register event watchers as long
		562	\& ... as they still have work to do (even an idle watcher will do..)
		563	\& ev_loop (my_loop, 0);
		564	\& ... jobs done. yeah!
445	.Ve	565	.Ve
446	.IP "ev_unloop (loop, how)" 4	566	.IP "ev_unloop (loop, how)" 4
447	.IX Item "ev_unloop (loop, how)"	567	.IX Item "ev_unloop (loop, how)"
448	Can be used to make a call to \f(CW\(C`ev_loop\(C'\fR return early (but only after it	568	Can be used to make a call to \f(CW\(C`ev_loop\(C'\fR return early (but only after it
449	has processed all outstanding events). The \f(CW\(C`how\(C'\fR argument must be either	569	has processed all outstanding events). The \f(CW\(C`how\(C'\fR argument must be either
…		…
463	example, libev itself uses this for its internal signal pipe: It is not	583	example, libev itself uses this for its internal signal pipe: It is not
464	visible to the libev user and should not keep \f(CW\(C`ev_loop\(C'\fR from exiting if	584	visible to the libev user and should not keep \f(CW\(C`ev_loop\(C'\fR from exiting if
465	no event watchers registered by it are active. It is also an excellent	585	no event watchers registered by it are active. It is also an excellent
466	way to do this for generic recurring timers or from within third-party	586	way to do this for generic recurring timers or from within third-party
467	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.	587	libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
		588	.Sp
		589	Example: create a signal watcher, but keep it from keeping \f(CW\(C`ev_loop\(C'\fR
		590	running when nothing else is active.
		591	.Sp
		592	.Vb 4
		593	\& struct dv_signal exitsig;
		594	\& ev_signal_init (&exitsig, sig_cb, SIGINT);
		595	\& ev_signal_start (myloop, &exitsig);
		596	\& evf_unref (myloop);
		597	.Ve
		598	.Sp
		599	Example: for some weird reason, unregister the above signal handler again.
		600	.Sp
		601	.Vb 2
		602	\& ev_ref (myloop);
		603	\& ev_signal_stop (myloop, &exitsig);
		604	.Ve
468	.SH "ANATOMY OF A WATCHER"	605	.SH "ANATOMY OF A WATCHER"
469	.IX Header "ANATOMY OF A WATCHER"	606	.IX Header "ANATOMY OF A WATCHER"
470	A watcher is a structure that you create and register to record your	607	A watcher is a structure that you create and register to record your
471	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to	608	interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
472	become readable, you would create an \f(CW\(C`ev_io\(C'\fR watcher for that:	609	become readable, you would create an \f(CW\(C`ev_io\(C'\fR watcher for that:
…		…
508	)\(C'\fR), and you can stop watching for events at any time by calling the	645	)\(C'\fR), and you can stop watching for events at any time by calling the
509	corresponding stop function (\f(CW\(C`ev_<type>_stop (loop, watcher )\*(C'\fR.	646	corresponding stop function (\f(CW\(C`ev_<type>_stop (loop, watcher )\*(C'\fR.
510	.PP	647	.PP
511	As long as your watcher is active (has been started but not stopped) you	648	As long as your watcher is active (has been started but not stopped) you
512	must not touch the values stored in it. Most specifically you must never	649	must not touch the values stored in it. Most specifically you must never
513	reinitialise it or call its set macro.	650	reinitialise it or call its \f(CW\(C`set\(C'\fR macro.
514	.PP
515	You can check whether an event is active by calling the \f(CW\*(C`ev_is_active
516	(watcher )\(C'\fR macro. To see whether an event is outstanding (but the
517	callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending
518	(watcher )\(C'\fR macro.
519	.PP	651	.PP
520	Each and every callback receives the event loop pointer as first, the	652	Each and every callback receives the event loop pointer as first, the
521	registered watcher structure as second, and a bitset of received events as	653	registered watcher structure as second, and a bitset of received events as
522	third argument.	654	third argument.
523	.PP	655	.PP
…		…
581	Libev will usually signal a few \(L"dummy\(R" events together with an error,	713	Libev will usually signal a few \(L"dummy\(R" events together with an error,
582	for example it might indicate that a fd is readable or writable, and if	714	for example it might indicate that a fd is readable or writable, and if
583	your callbacks is well-written it can just attempt the operation and cope	715	your callbacks is well-written it can just attempt the operation and cope
584	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded	716	with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded
585	programs, though, so beware.	717	programs, though, so beware.
		718	.Sh "\s-1SUMMARY\s0 \s-1OF\s0 \s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0"
		719	.IX Subsection "SUMMARY OF GENERIC WATCHER FUNCTIONS"
		720	In the following description, \f(CW\(C`TYPE\(C'\fR stands for the watcher type,
		721	e.g. \f(CW\(C`timer\(C'\fR for \f(CW\(C`ev_timer\(C'\fR watchers and \f(CW\(C`io\(C'\fR for \f(CW\(C`ev_io\(C'\fR watchers.
		722	.ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4
		723	.el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4
		724	.IX Item "ev_init (ev_TYPE *watcher, callback)"
		725	This macro initialises the generic portion of a watcher. The contents
		726	of the watcher object can be arbitrary (so \f(CW\(C`malloc\(C'\fR will do). Only
		727	the generic parts of the watcher are initialised, you \fIneed\fR to call
		728	the type-specific \f(CW\(C`ev_TYPE_set\(C'\fR macro afterwards to initialise the
		729	type-specific parts. For each type there is also a \f(CW\(C`ev_TYPE_init\(C'\fR macro
		730	which rolls both calls into one.
		731	.Sp
		732	You can reinitialise a watcher at any time as long as it has been stopped
		733	(or never started) and there are no pending events outstanding.
		734	.Sp
		735	The callbakc is always of type \f(CW\(C`void ()(ev_loop loop, ev_TYPE watcher,
		736	int revents)\*(C'\fR.
		737	.ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4
		738	.el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4
		739	.IX Item "ev_TYPE_set (ev_TYPE *, [args])"
		740	This macro initialises the type-specific parts of a watcher. You need to
		741	call \f(CW\(C`ev_init\(C'\fR at least once before you call this macro, but you can
		742	call \f(CW\(C`ev_TYPE_set\(C'\fR any number of times. You must not, however, call this
		743	macro on a watcher that is active (it can be pending, however, which is a
		744	difference to the \f(CW\(C`ev_init\(C'\fR macro).
		745	.Sp
		746	Although some watcher types do not have type-specific arguments
		747	(e.g. \f(CW\(C`ev_prepare\(C'\fR) you still need to call its \f(CW\(C`set\(C'\fR macro.
		748	.ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4
		749	.el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4
		750	.IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])"
		751	This convinience macro rolls both \f(CW\(C`ev_init\(C'\fR and \f(CW\(C`ev_TYPE_set\(C'\fR macro
		752	calls into a single call. This is the most convinient method to initialise
		753	a watcher. The same limitations apply, of course.
		754	.ie n .IP """ev_TYPE_start"" (loop , ev_TYPE watcher)" 4
		755	.el .IP "\f(CWev_TYPE_start\fR (loop , ev_TYPE watcher)" 4
		756	.IX Item "ev_TYPE_start (loop , ev_TYPE watcher)"
		757	Starts (activates) the given watcher. Only active watchers will receive
		758	events. If the watcher is already active nothing will happen.
		759	.ie n .IP """ev_TYPE_stop"" (loop , ev_TYPE watcher)" 4
		760	.el .IP "\f(CWev_TYPE_stop\fR (loop , ev_TYPE watcher)" 4
		761	.IX Item "ev_TYPE_stop (loop , ev_TYPE watcher)"
		762	Stops the given watcher again (if active) and clears the pending
		763	status. It is possible that stopped watchers are pending (for example,
		764	non-repeating timers are being stopped when they become pending), but
		765	\&\f(CW\(C`ev_TYPE_stop\(C'\fR ensures that the watcher is neither active nor pending. If
		766	you want to free or reuse the memory used by the watcher it is therefore a
		767	good idea to always call its \f(CW\(C`ev_TYPE_stop\(C'\fR function.
		768	.IP "bool ev_is_active (ev_TYPE *watcher)" 4
		769	.IX Item "bool ev_is_active (ev_TYPE *watcher)"
		770	Returns a true value iff the watcher is active (i.e. it has been started
		771	and not yet been stopped). As long as a watcher is active you must not modify
		772	it.
		773	.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
		774	.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
		775	Returns a true value iff the watcher is pending, (i.e. it has outstanding
		776	events but its callback has not yet been invoked). As long as a watcher
		777	is pending (but not active) you must not call an init function on it (but
		778	\&\f(CW\(C`ev_TYPE_set\(C'\fR is safe) and you must make sure the watcher is available to
		779	libev (e.g. you cnanot \f(CW\(C`free ()\(C'\fR it).
		780	.IP "callback = ev_cb (ev_TYPE *watcher)" 4
		781	.IX Item "callback = ev_cb (ev_TYPE *watcher)"
		782	Returns the callback currently set on the watcher.
		783	.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
		784	.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
		785	Change the callback. You can change the callback at virtually any time
		786	(modulo threads).
586	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"	787	.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
587	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"	788	.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
588	Each watcher has, by default, a member \f(CW\(C`void data\*(C'\fR that you can change	789	Each watcher has, by default, a member \f(CW\(C`void data\*(C'\fR that you can change
589	and read at any time, libev will completely ignore it. This can be used	790	and read at any time, libev will completely ignore it. This can be used
590	to associate arbitrary data with your watcher. If you need more data and	791	to associate arbitrary data with your watcher. If you need more data and
…		…
660	\&\f(CW\(C`EVBACKEND_SELECT\(C'\fR or \f(CW\(C`EVBACKEND_POLL\(C'\fR, which don't suffer from this	861	\&\f(CW\(C`EVBACKEND_SELECT\(C'\fR or \f(CW\(C`EVBACKEND_POLL\(C'\fR, which don't suffer from this
661	problem. Also note that it is quite easy to have your callback invoked	862	problem. Also note that it is quite easy to have your callback invoked
662	when the readyness condition is no longer valid even when employing	863	when the readyness condition is no longer valid even when employing
663	typical ways of handling events, so its a good idea to use non-blocking	864	typical ways of handling events, so its a good idea to use non-blocking
664	I/O unconditionally.	865	I/O unconditionally.
		866	.PP
		867	Example: call \f(CW\(C`stdin_readable_cb\(C'\fR when \s-1STDIN_FILENO\s0 has become, well
		868	readable, but only once. Since it is likely line\-buffered, you could
		869	attempt to read a whole line in the callback:
		870	.PP
		871	.Vb 6
		872	\& static void
		873	\& stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
		874	\& {
		875	\& ev_io_stop (loop, w);
		876	\& .. read from stdin here (or from w->fd) and haqndle any I/O errors
		877	\& }
		878	.Ve
		879	.PP
		880	.Vb 6
		881	\& ...
		882	\& struct ev_loop *loop = ev_default_init (0);
		883	\& struct ev_io stdin_readable;
		884	\& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
		885	\& ev_io_start (loop, &stdin_readable);
		886	\& ev_loop (loop, 0);
		887	.Ve
665	.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts"	888	.ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts"
666	.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts"	889	.el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts"
667	.IX Subsection "ev_timer - relative and optionally recurring timeouts"	890	.IX Subsection "ev_timer - relative and optionally recurring timeouts"
668	Timer watchers are simple relative timers that generate an event after a	891	Timer watchers are simple relative timers that generate an event after a
669	given time, and optionally repeating in regular intervals after that.	892	given time, and optionally repeating in regular intervals after that.
…		…
719	seconds of inactivity on the socket. The easiest way to do this is to	942	seconds of inactivity on the socket. The easiest way to do this is to
720	configure an \f(CW\(C`ev_timer\(C'\fR with after=repeat=60 and calling ev_timer_again each	943	configure an \f(CW\(C`ev_timer\(C'\fR with after=repeat=60 and calling ev_timer_again each
721	time you successfully read or write some data. If you go into an idle	944	time you successfully read or write some data. If you go into an idle
722	state where you do not expect data to travel on the socket, you can stop	945	state where you do not expect data to travel on the socket, you can stop
723	the timer, and again will automatically restart it if need be.	946	the timer, and again will automatically restart it if need be.
		947	.PP
		948	Example: create a timer that fires after 60 seconds.
		949	.PP
		950	.Vb 5
		951	\& static void
		952	\& one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
		953	\& {
		954	\& .. one minute over, w is actually stopped right here
		955	\& }
		956	.Ve
		957	.PP
		958	.Vb 3
		959	\& struct ev_timer mytimer;
		960	\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
		961	\& ev_timer_start (loop, &mytimer);
		962	.Ve
		963	.PP
		964	Example: create a timeout timer that times out after 10 seconds of
		965	inactivity.
		966	.PP
		967	.Vb 5
		968	\& static void
		969	\& timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
		970	\& {
		971	\& .. ten seconds without any activity
		972	\& }
		973	.Ve
		974	.PP
		975	.Vb 4
		976	\& struct ev_timer mytimer;
		977	\& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
		978	\& ev_timer_again (&mytimer); /* start timer */
		979	\& ev_loop (loop, 0);
		980	.Ve
		981	.PP
		982	.Vb 3
		983	\& // and in some piece of code that gets executed on any "activity":
		984	\& // reset the timeout to start ticking again at 10 seconds
		985	\& ev_timer_again (&mytimer);
		986	.Ve
724	.ie n .Sh """ev_periodic"" \- to cron or not to cron"	987	.ie n .Sh """ev_periodic"" \- to cron or not to cron"
725	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron"	988	.el .Sh "\f(CWev_periodic\fP \- to cron or not to cron"
726	.IX Subsection "ev_periodic - to cron or not to cron"	989	.IX Subsection "ev_periodic - to cron or not to cron"
727	Periodic watchers are also timers of a kind, but they are very versatile	990	Periodic watchers are also timers of a kind, but they are very versatile
728	(and unfortunately a bit complex).	991	(and unfortunately a bit complex).
…		…
820	.IX Item "ev_periodic_again (loop, ev_periodic *)"	1083	.IX Item "ev_periodic_again (loop, ev_periodic *)"
821	Simply stops and restarts the periodic watcher again. This is only useful	1084	Simply stops and restarts the periodic watcher again. This is only useful
822	when you changed some parameters or the reschedule callback would return	1085	when you changed some parameters or the reschedule callback would return
823	a different time than the last time it was called (e.g. in a crond like	1086	a different time than the last time it was called (e.g. in a crond like
824	program when the crontabs have changed).	1087	program when the crontabs have changed).
		1088	.PP
		1089	Example: call a callback every hour, or, more precisely, whenever the
		1090	system clock is divisible by 3600. The callback invocation times have
		1091	potentially a lot of jittering, but good long-term stability.
		1092	.PP
		1093	.Vb 5
		1094	\& static void
		1095	\& clock_cb (struct ev_loop loop, struct ev_io w, int revents)
		1096	\& {
		1097	\& ... its now a full hour (UTC, or TAI or whatever your clock follows)
		1098	\& }
		1099	.Ve
		1100	.PP
		1101	.Vb 3
		1102	\& struct ev_periodic hourly_tick;
		1103	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
		1104	\& ev_periodic_start (loop, &hourly_tick);
		1105	.Ve
		1106	.PP
		1107	Example: the same as above, but use a reschedule callback to do it:
		1108	.PP
		1109	.Vb 1
		1110	\& #include <math.h>
		1111	.Ve
		1112	.PP
		1113	.Vb 5
		1114	\& static ev_tstamp
		1115	\& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
		1116	\& {
		1117	\& return fmod (now, 3600.) + 3600.;
		1118	\& }
		1119	.Ve
		1120	.PP
		1121	.Vb 1
		1122	\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
		1123	.Ve
		1124	.PP
		1125	Example: call a callback every hour, starting now:
		1126	.PP
		1127	.Vb 4
		1128	\& struct ev_periodic hourly_tick;
		1129	\& ev_periodic_init (&hourly_tick, clock_cb,
		1130	\& fmod (ev_now (loop), 3600.), 3600., 0);
		1131	\& ev_periodic_start (loop, &hourly_tick);
		1132	.Ve
825	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled"	1133	.ie n .Sh """ev_signal"" \- signal me when a signal gets signalled"
826	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled"	1134	.el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled"
827	.IX Subsection "ev_signal - signal me when a signal gets signalled"	1135	.IX Subsection "ev_signal - signal me when a signal gets signalled"
828	Signal watchers will trigger an event when the process receives a specific	1136	Signal watchers will trigger an event when the process receives a specific
829	signal one or more times. Even though signals are very asynchronous, libev	1137	signal one or more times. Even though signals are very asynchronous, libev
…		…
859	\&\fIany\fR process if \f(CW\(C`pid\(C'\fR is specified as \f(CW0\fR). The callback can look	1167	\&\fIany\fR process if \f(CW\(C`pid\(C'\fR is specified as \f(CW0\fR). The callback can look
860	at the \f(CW\(C`rstatus\(C'\fR member of the \f(CW\(C`ev_child\(C'\fR watcher structure to see	1168	at the \f(CW\(C`rstatus\(C'\fR member of the \f(CW\(C`ev_child\(C'\fR watcher structure to see
861	the status word (use the macros from \f(CW\(C`sys/wait.h\(C'\fR and see your systems	1169	the status word (use the macros from \f(CW\(C`sys/wait.h\(C'\fR and see your systems
862	\&\f(CW\(C`waitpid\(C'\fR documentation). The \f(CW\(C`rpid\(C'\fR member contains the pid of the	1170	\&\f(CW\(C`waitpid\(C'\fR documentation). The \f(CW\(C`rpid\(C'\fR member contains the pid of the
863	process causing the status change.	1171	process causing the status change.
		1172	.PP
		1173	Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
		1174	.PP
		1175	.Vb 5
		1176	\& static void
		1177	\& sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
		1178	\& {
		1179	\& ev_unloop (loop, EVUNLOOP_ALL);
		1180	\& }
		1181	.Ve
		1182	.PP
		1183	.Vb 3
		1184	\& struct ev_signal signal_watcher;
		1185	\& ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1186	\& ev_signal_start (loop, &sigint_cb);
		1187	.Ve
864	.ie n .Sh """ev_idle"" \- when you've got nothing better to do"	1188	.ie n .Sh """ev_idle"" \- when you've got nothing better to do"
865	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do"	1189	.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do"
866	.IX Subsection "ev_idle - when you've got nothing better to do"	1190	.IX Subsection "ev_idle - when you've got nothing better to do"
867	Idle watchers trigger events when there are no other events are pending	1191	Idle watchers trigger events when there are no other events are pending
868	(prepare, check and other idle watchers do not count). That is, as long	1192	(prepare, check and other idle watchers do not count). That is, as long
…		…
882	.IP "ev_idle_init (ev_signal *, callback)" 4	1206	.IP "ev_idle_init (ev_signal *, callback)" 4
883	.IX Item "ev_idle_init (ev_signal *, callback)"	1207	.IX Item "ev_idle_init (ev_signal *, callback)"
884	Initialises and configures the idle watcher \- it has no parameters of any	1208	Initialises and configures the idle watcher \- it has no parameters of any
885	kind. There is a \f(CW\(C`ev_idle_set\(C'\fR macro, but using it is utterly pointless,	1209	kind. There is a \f(CW\(C`ev_idle_set\(C'\fR macro, but using it is utterly pointless,
886	believe me.	1210	believe me.
		1211	.PP
		1212	Example: dynamically allocate an \f(CW\(C`ev_idle\(C'\fR, start it, and in the
		1213	callback, free it. Alos, use no error checking, as usual.
		1214	.PP
		1215	.Vb 7
		1216	\& static void
		1217	\& idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
		1218	\& {
		1219	\& free (w);
		1220	\& // now do something you wanted to do when the program has
		1221	\& // no longer asnything immediate to do.
		1222	\& }
		1223	.Ve
		1224	.PP
		1225	.Vb 3
		1226	\& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
		1227	\& ev_idle_init (idle_watcher, idle_cb);
		1228	\& ev_idle_start (loop, idle_cb);
		1229	.Ve
887	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop"	1230	.ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop"
888	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop"	1231	.el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop"
889	.IX Subsection "ev_prepare and ev_check - customise your event loop"	1232	.IX Subsection "ev_prepare and ev_check - customise your event loop"
890	Prepare and check watchers are usually (but not always) used in tandem:	1233	Prepare and check watchers are usually (but not always) used in tandem:
891	prepare watchers get invoked before the process blocks and check watchers	1234	prepare watchers get invoked before the process blocks and check watchers
892	afterwards.	1235	afterwards.
893	.PP	1236	.PP
894	Their main purpose is to integrate other event mechanisms into libev. This	1237	Their main purpose is to integrate other event mechanisms into libev and
895	could be used, for example, to track variable changes, implement your own	1238	their use is somewhat advanced. This could be used, for example, to track
896	watchers, integrate net-snmp or a coroutine library and lots more.	1239	variable changes, implement your own watchers, integrate net-snmp or a
		1240	coroutine library and lots more.
897	.PP	1241	.PP
898	This is done by examining in each prepare call which file descriptors need	1242	This is done by examining in each prepare call which file descriptors need
899	to be watched by the other library, registering \f(CW\(C`ev_io\(C'\fR watchers for	1243	to be watched by the other library, registering \f(CW\(C`ev_io\(C'\fR watchers for
900	them and starting an \f(CW\(C`ev_timer\(C'\fR watcher for any timeouts (many libraries	1244	them and starting an \f(CW\(C`ev_timer\(C'\fR watcher for any timeouts (many libraries
901	provide just this functionality). Then, in the check watcher you check for	1245	provide just this functionality). Then, in the check watcher you check for
…		…
919	.IX Item "ev_check_init (ev_check *, callback)"	1263	.IX Item "ev_check_init (ev_check *, callback)"
920	.PD	1264	.PD
921	Initialises and configures the prepare or check watcher \- they have no	1265	Initialises and configures the prepare or check watcher \- they have no
922	parameters of any kind. There are \f(CW\(C`ev_prepare_set\(C'\fR and \f(CW\(C`ev_check_set\(C'\fR	1266	parameters of any kind. There are \f(CW\(C`ev_prepare_set\(C'\fR and \f(CW\(C`ev_check_set\(C'\fR
923	macros, but using them is utterly, utterly and completely pointless.	1267	macros, but using them is utterly, utterly and completely pointless.
		1268	.PP
		1269	Example: TODO.
		1270	.ie n .Sh """ev_embed"" \- when one backend isn't enough"
		1271	.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough"
		1272	.IX Subsection "ev_embed - when one backend isn't enough"
		1273	This is a rather advanced watcher type that lets you embed one event loop
		1274	into another (currently only \f(CW\(C`ev_io\(C'\fR events are supported in the embedded
		1275	loop, other types of watchers might be handled in a delayed or incorrect
		1276	fashion and must not be used).
		1277	.PP
		1278	There are primarily two reasons you would want that: work around bugs and
		1279	prioritise I/O.
		1280	.PP
		1281	As an example for a bug workaround, the kqueue backend might only support
		1282	sockets on some platform, so it is unusable as generic backend, but you
		1283	still want to make use of it because you have many sockets and it scales
		1284	so nicely. In this case, you would create a kqueue-based loop and embed it
		1285	into your default loop (which might use e.g. poll). Overall operation will
		1286	be a bit slower because first libev has to poll and then call kevent, but
		1287	at least you can use both at what they are best.
		1288	.PP
		1289	As for prioritising I/O: rarely you have the case where some fds have
		1290	to be watched and handled very quickly (with low latency), and even
		1291	priorities and idle watchers might have too much overhead. In this case
		1292	you would put all the high priority stuff in one loop and all the rest in
		1293	a second one, and embed the second one in the first.
		1294	.PP
		1295	As long as the watcher is active, the callback will be invoked every time
		1296	there might be events pending in the embedded loop. The callback must then
		1297	call \f(CW\(C`ev_embed_sweep (mainloop, watcher)\(C'\fR to make a single sweep and invoke
		1298	their callbacks (you could also start an idle watcher to give the embedded
		1299	loop strictly lower priority for example). You can also set the callback
		1300	to \f(CW0\fR, in which case the embed watcher will automatically execute the
		1301	embedded loop sweep.
		1302	.PP
		1303	As long as the watcher is started it will automatically handle events. The
		1304	callback will be invoked whenever some events have been handled. You can
		1305	set the callback to \f(CW0\fR to avoid having to specify one if you are not
		1306	interested in that.
		1307	.PP
		1308	Also, there have not currently been made special provisions for forking:
		1309	when you fork, you not only have to call \f(CW\(C`ev_loop_fork\(C'\fR on both loops,
		1310	but you will also have to stop and restart any \f(CW\(C`ev_embed\(C'\fR watchers
		1311	yourself.
		1312	.PP
		1313	Unfortunately, not all backends are embeddable, only the ones returned by
		1314	\&\f(CW\(C`ev_embeddable_backends\(C'\fR are, which, unfortunately, does not include any
		1315	portable one.
		1316	.PP
		1317	So when you want to use this feature you will always have to be prepared
		1318	that you cannot get an embeddable loop. The recommended way to get around
		1319	this is to have a separate variables for your embeddable loop, try to
		1320	create it, and if that fails, use the normal loop for everything:
		1321	.PP
		1322	.Vb 3
		1323	\& struct ev_loop *loop_hi = ev_default_init (0);
		1324	\& struct ev_loop *loop_lo = 0;
		1325	\& struct ev_embed embed;
		1326	.Ve
		1327	.PP
		1328	.Vb 5
		1329	\& // see if there is a chance of getting one that works
		1330	\& // (remember that a flags value of 0 means autodetection)
		1331	\& loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
		1332	\& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
		1333	\& : 0;
		1334	.Ve
		1335	.PP
		1336	.Vb 8
		1337	\& // if we got one, then embed it, otherwise default to loop_hi
		1338	\& if (loop_lo)
		1339	\& {
		1340	\& ev_embed_init (&embed, 0, loop_lo);
		1341	\& ev_embed_start (loop_hi, &embed);
		1342	\& }
		1343	\& else
		1344	\& loop_lo = loop_hi;
		1345	.Ve
		1346	.IP "ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)" 4
		1347	.IX Item "ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)"
		1348	.PD 0
		1349	.IP "ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)" 4
		1350	.IX Item "ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)"
		1351	.PD
		1352	Configures the watcher to embed the given loop, which must be
		1353	embeddable. If the callback is \f(CW0\fR, then \f(CW\(C`ev_embed_sweep\(C'\fR will be
		1354	invoked automatically, otherwise it is the responsibility of the callback
		1355	to invoke it (it will continue to be called until the sweep has been done,
		1356	if you do not want thta, you need to temporarily stop the embed watcher).
		1357	.IP "ev_embed_sweep (loop, ev_embed *)" 4
		1358	.IX Item "ev_embed_sweep (loop, ev_embed *)"
		1359	Make a single, non-blocking sweep over the embedded loop. This works
		1360	similarly to \f(CW\(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\(C'\fR, but in the most
		1361	apropriate way for embedded loops.
924	.SH "OTHER FUNCTIONS"	1362	.SH "OTHER FUNCTIONS"
925	.IX Header "OTHER FUNCTIONS"	1363	.IX Header "OTHER FUNCTIONS"
926	There are some other functions of possible interest. Described. Here. Now.	1364	There are some other functions of possible interest. Described. Here. Now.
927	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4	1365	.IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4
928	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"	1366	.IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)"
…		…
957	.Ve	1395	.Ve
958	.Sp	1396	.Sp
959	.Vb 1	1397	.Vb 1
960	\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1398	\& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
961	.Ve	1399	.Ve
962	.IP "ev_feed_event (loop, watcher, int events)" 4	1400	.IP "ev_feed_event (ev_loop , watcher , int revents)" 4
963	.IX Item "ev_feed_event (loop, watcher, int events)"	1401	.IX Item "ev_feed_event (ev_loop , watcher , int revents)"
964	Feeds the given event set into the event loop, as if the specified event	1402	Feeds the given event set into the event loop, as if the specified event
965	had happened for the specified watcher (which must be a pointer to an	1403	had happened for the specified watcher (which must be a pointer to an
966	initialised but not necessarily started event watcher).	1404	initialised but not necessarily started event watcher).
967	.IP "ev_feed_fd_event (loop, int fd, int revents)" 4	1405	.IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4
968	.IX Item "ev_feed_fd_event (loop, int fd, int revents)"	1406	.IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)"
969	Feed an event on the given fd, as if a file descriptor backend detected	1407	Feed an event on the given fd, as if a file descriptor backend detected
970	the given events it.	1408	the given events it.
971	.IP "ev_feed_signal_event (loop, int signum)" 4	1409	.IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4
972	.IX Item "ev_feed_signal_event (loop, int signum)"	1410	.IX Item "ev_feed_signal_event (ev_loop *loop, int signum)"
973	Feed an event as if the given signal occured (loop must be the default loop!).	1411	Feed an event as if the given signal occured (\f(CW\(C`loop\(C'\fR must be the default
		1412	loop!).
974	.SH "LIBEVENT EMULATION"	1413	.SH "LIBEVENT EMULATION"
975	.IX Header "LIBEVENT EMULATION"	1414	.IX Header "LIBEVENT EMULATION"
976	Libev offers a compatibility emulation layer for libevent. It cannot	1415	Libev offers a compatibility emulation layer for libevent. It cannot
977	emulate the internals of libevent, so here are some usage hints:	1416	emulate the internals of libevent, so here are some usage hints:
978	.IP "* Use it by including <event.h>, as usual." 4	1417	.IP "* Use it by including <event.h>, as usual." 4

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Comparing libev/ev.3 (file contents): Revision 1.7 by root, Fri Nov 23 08:36:35 2007 UTC vs. Revision 1.11 by root, Sat Nov 24 07:14:26 2007 UTC

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Comparing libev/ev.3 (file contents):
Revision 1.7 by root, Fri Nov 23 08:36:35 2007 UTC vs.
Revision 1.11 by root, Sat Nov 24 07:14:26 2007 UTC